Temperature compensation in integrated CMOS-MEMS scanning probe microscopes

The authors report on the operation of complementary metal-oxide semiconductor microelectromechanical system (MEMS) scanning probe microscope (SPM) with integrated three-dimensional electrothermal actuation and three-axis position sensing. Conventional SPM makes use of piezoelectric positioning systems which are bulky (leading to thermal drift and poor vibration immunity) and suffer from inherent creep (leading to image distortion). The scanner design is intended to leverage the myriad physical benefits of dimensional scaling to improve the performance and to reduce the barrier to entry for SPM ownership when compared to the state-of-the-art. However, the integration of multiple electrothermal actuators on chip introduces several complications owing to coupling between electrical, thermal and mechanical domains. The focus of this Letter is to discuss the origins of these effects, and the strategies that are implemented to mitigate them. Specifically, the authors discuss the open-loop and closed-loop control methods that are used to drive the lateral and vertical actuators and propose and verify a method to compensate for the parasitic effects observed in the piezoresistive force sensors. To the best of the authors´ knowledge, this is the first integrated MEMS-SPM with multiple imaging modes that can image a sample without the need for off-chip scanners or laser-based position sensing.